Carbohydrate-Dependent, Exercise-Induced Gastrointestinal Distress

Gastrointestinal (GI) problems are a common concern of athletes during intense exercise. Ultimately, these symptoms can impair performance and possibly prevent athletes from winning or even finishing a race. The main causes of GI problems during exercise are mechanical, ischemic and nutritional factors. Among the nutritional factors, a high intake of carbohydrate and hyperosmolar solutions increases GI problems. A number of nutritional manipulations have been proposed to minimize gastrointestinal symptoms, including the use of multiple transportable carbohydrates. This type of CHO intake increases the oxidation rates and can prevent the accumulation of carbohydrate in the intestine. Glucose (6%) or glucose plus fructose (8%-10%) beverages are recommended in order to increase CHO intake while avoiding the gastric emptying delay. Training the gut with high intake of CHO may increase absorption capacity and probably prevent GI distress. CHO mouth rinse may be a good strategy to enhance performance without using GI tract in exercises lasting less than an hour. Future strategies should be investigated comparing different CHO types, doses, and concentration in exercises with the same characteristics.

Rating of perceived exertion as a tool for prescribing and self regulating interval training: a pilot study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Prescribing and regulating exercise with RPE after heart transplant: a pilot study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Short-term low-intensity blood flow restricted interval training improves both aerobic fitness and muscle strength

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

An experimental model for resistance exercise in rodents

This study aimed to develop an equipment and system of resistance exercise (RE), based on squat-type exercise for rodents, with control of training variables. We developed an operant conditioning system composed of sound, light and feeding devices that allowed optimized RE performance by the animal. With this system, it is not necessary to impose fasting or electric shock for the animal to perform the task proposed (muscle contraction). Furthermore, it is possible to perform muscle function tests in vivo within the context of the exercise proposed and control variables such as intensity, volume (sets and repetitions), and exercise session length, rest interval between sets and repetitions, and concentric strength. Based on the experiments conducted, we demonstrated that the model proposed is able to perform more specific control of other RE variables, especially rest interval between sets and repetitions, and encourages the animal to exercise through short-term energy restriction and "disturbing" stimulus that do not promote alterations in body weight. Therefore, despite experimental limitations, we believe that this RE apparatus is closer to the physiological context observed in humans.

Influence of different resistance exercise loading schemes on mechanical power output in work to rest ratio - equated and - nonequated conditions

Paulo CA, Roschel H, Ugrinowitsch C, Kobal R and Tricoli V. Influence of different resistance exercise loading schemes on mechanical power output in work to rest ratio-equated and -nonequated conditions. J Strength Cond Res 26(5): 1308-1312, 2012-It is well known that most sports are characterized by the performance of intermittent high-intensity actions, requiring high muscle power production within different intervals. In fact, the manipulation of the exercise to rest ratio in muscle power training programs may constitute an interesting strategy when considering the specific performance demand of a given sport modality. Thus, the aim of this study was to evaluate the influence of different schemes of rest intervals and number of repetitions per set on muscle power production in the squat exercise between exercise to rest ratio-equated and -nonequated conditions. Nineteen young males (age: 25.7 +/- 4.4 years; weight: 81.3 +/- 13.7 kg; height: 178.1 +/- 5.5 cm) were randomly submitted to 3 different resistance exercise loading schemes, as follows: short-set short-interval condition (SSSI; 12 sets of 3 repetitions with a 27.3-second interval between sets); short-set long-interval condition (SSLI; 12 sets of 3 repetitions with a 60-second interval between sets); long-set long-interval (LSLI; 6 sets of 6 repetitions with a 60-second rest interval between sets). The main finding of the present study is that the lower exercise to rest ratio protocol (SSLI) resulted in greater average power production (601.88 +/- 142.48 W) when compared with both SSSI and LSLI (581.86 +/- 113.18 W; 578 +/- 138.78 W, respectively). Additionally, both the exercise to rest ratio-equated conditions presented similar performance and metabolic results. In summary, these findings suggest that shorter rest intervals may fully restore the individual's ability to produce muscle power if a smaller exercise volume per set is performed and that lower exercise to rest ratio protocols result in greater average power production when compared with higher ratio ones.

Pontomedullary and hypothalamic distribution of Fos-like immunoreactive neurons after acute exercise in rats

During exercise, intense brain activity orchestrates an increase in muscle tension. Additionally, there is an increase in cardiac output and ventilation to compensate the increased metabolic demand of muscle activity and to facilitate the removal of CO2 from and the delivery of O-2 to tissues. Here we tested the hypothesis that a subset of pontomedullary and hypothalamic neurons could be activated during dynamic acute exercise. Male Wistar rats (250-350 g) were divided into an exercise group (n = 12) that ran on a treadmill and a no-exercise group (n = 7). Immunohistochemistry of pontomedullary and hypothalamic sections to identify activation (c-Fos expression) of cardiorespiratory areas showed that the no-exercise rats exhibited minimal Fos expression. In contrast, there was intense activation of the nucleus of the solitary tract, the ventrolateral medulla (including the presumed central chemoreceptor neurons in the retrotrapezoid/parafacial region), the lateral parabrachial nucleus, the Kolliker-Fuse region, the perifornical region, which includes the perifornical area and the lateral hypothalamus, the dorsal medial hypothalamus, and the paraventricular nucleus of the hypothalamus after running exercise. Additionally, we observed Fos immunoreactivity in catecholaminergic neurons within the ventrolateral medulla (C1 region) without Fos expression in the A2, A5 and A7 neurons. In summary, we show for the first time that after acute exercise there is an intense activation of brain areas crucial for cardiorespiratory control. Possible involvement of the central command mechanism should be considered. Our results suggest whole brain-specific mobilization to correct and compensate the homeostatic changes produced by acute exercise. (c) 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

Glutamatergic neurotransmission in the hypothalamus PVN on heart rate variability in exercise trained rats

The paraventricular nucleus of hypothalamus (PVN) is a well known site of integration for autonomic and cardiovascular responses, and the glutamate neurotransmitter plays an important role. The aim of our study was to evaluate the cardiovascular parameters and autonomic modulation by means of spectral analysis after ionotropic glutamate receptor inhibition in the PVN in conscious sedentary (S) or swimming trained (ST) rats. After exercise training protocol, adult male Wistar rats, instrumented with guide cannulae to PVN and artery and vein catheters were submitted to mean arterial pressure (MAP) and heart rate (HR) recording. At baseline, physical training induced a resting bradycardia (S: 379 +/- 3, ST: 349 +/- 2 bpm, P<0.05) and promoted adaptations in HRV characterized by an increase of HF in normalized values and a decrease of LF in absolute and normalized units compared with the sedentary group. Microinjection of kynurenic acid (KYNA) in the PVN of sedentary and trained rats promoted decreases in MAP and HR, but the decrease in HR was smaller in the trained animals (Delta HRS: -48 +/- 7, ST: -28 +/- 4 bpm, P<0.05). Furthermore, the differences in baseline parameters of pulse interval, found between sedentary and trained animals, disappeared after KYNA microinjection in the PVN. Our data suggest that the cardiovascular and autonomic adaptations to the heart induced by exercise training may involve glutamatergic mechanisms in the PVN. (C) 2012 Elsevier B.V. All rights reserved.

Probiotic cheese attenuates exercise-induced immune suppression in Wistar rats

Intense physical activity results in a substantial volume of stress and hence a significant probability of immunosuppression in athletes, with milk proteins being, perhaps, the most recommended protein supplements. Consumption of a probiotic cheese can attenuate immune suppression induced by exhausting exercise in rats. A popular Brazilian fresh cheese (Minas Frescal cheese) containing Lactobacillus acidophilus LA14 and Bifidobacterium longum BL05 was fed for 2 wk to adult Wistar rats, which then were brought to exhaustion on the treadmill. Two hours after exhaustion, the rats were killed and material was collected for the determination of serum uric acid, total and high-density lipoprotein cholesterol fraction, total protein, triacylglycerols, aspartate aminotransferase, alanine aminotransferase, creatine kinase, and blood cell (monocyte, lymphocyte, neutrophil, and leukocyte) counts. Exercise was efficient in reducing lymphocyte counts, irrespective of the type of ingested cheese, but the decrease in the group fed the probiotic cheese was 22% compared with 48% in the animals fed regular cheese. Monocyte counts were unaltered in the rats fed probiotic cheese compared with a significant decrease in the rats fed the regular cheese. Most importantly, ingestion of the probiotic cheese resulted in a >100% increase in serum high-density lipoprotein cholesterol and a 50% decrease in triacylglycerols. We conclude that probiotic Minas Reseal cheese may be a viable alternative to enhance the immune system and could be used to prevent infections, particularly those related to the physical overexertion of athletes.

Aerobic exercise training delays cardiac dysfunction and improves autonomic control of circulation in diabetic rats undergoing myocardial infarction

Background: Exercise training (ET) has been used as a nonpharmacological strategy for treatment of diabetes and myocardial infarction (MI) separately. We evaluated the effects ET on functional and molecular left ventricular (LV) parameters as well as on autonomic function and mortality in diabetics after MI. Methods and Results: Male Wistar rats were divided into control (C), sedentary-diabetic infarcted (SDI), and trained-diabetic infarcted (TDI) groups. MI was induced after 15 days of streptozotocin-diabetes induction. Seven days after MI, the trained group underwent ET protocol (90 days, 50-70% maximal oxygen consumption-VO(2)max). LV function was evaluated noninvasively and invasively; baroreflex sensitivity, pulse interval variability, cardiac output, tissue blood flows, VEGF mRNA and protein, HIF1-alpha mRNA, and Ca2+ handling proteins were measured. MI area was reduced in TDI (21 +/- 4%) compared with SDI (38 +/- 4%). ET induced improvement in cardiac function, hemodynamics, and tissue blood flows. These changes were probable consequences of a better expression of Ca2+ handling proteins, increased VEGF mRNA and protein expression as well as improvement in autonomic function, that resulted in reduction of mortality in TDI (33%) compared with SDI (68%) animals. Conclusions: ET reduced cardiac and peripheral dysfunction and preserved autonomic control in diabetic infarcted rats. Consequently, these changes resulted in improved VO(2)max and survival after MI. (J Cardiac Fail 2012; 18:734-744)

Physical exercise improves cardiac autonomic modulation in hypertensive patients independently of angiotensin-converting enzyme inhibitor treatment

We investigated the influence of angiotensin-converting enzyme inhibitor (ACEi) treatment and physical exercise on arterial pressure (AP) and heart rate variability (HRV) in volunteer patients with hypertension. A total of 54 sedentary volunteers were divided into three groups: normotensive (NT Group), hypertensive (HT Group) and HT volunteers treated with ACEi (ACEi Group). All volunteers underwent an aerobic physical-training protocol for 15 weeks. HRV was investigated using a spectral analysis of a time series of R-R interval (RRi) that was obtained in a supine position and during a tilt test. Physical training promoted a significant reduction in the mean arterial pressure of the HT group (113 +/- 3 vs. 106 +/- 1 mm Hg) and the ACEi group (104 +/- 2 vs. 98 +/- 2 mm Hg). Spectral analysis of RRi in the supine position before physical training demonstrated that the NT and ACEi groups had similar values at low frequency (LF; 0.04-0.15 Hz) and high frequency (HF; 0.15-0.5 Hz) oscillations. The HT group had an increase in LF oscillations in absolute and normalized units and a decrease in HF oscillations in normalized units compared with the other groups. The HT group had the lowest responses to the tilt test during LF oscillations in normalized units. Physical training improved the autonomic modulation of the heart rate in the supine position only in the HT group. Physical training promoted a similar increase in autonomic modulation responses in the tilt test in all groups. Our findings show that aerobic physical training improves cardiac autonomic modulation in HT volunteers independently of ACEi treatment. Hypertension Research (2012) 35, 82-87; doi:10.1038/hr.2011.162; published online 29 September 2011

Does land-based exercise reduce pain and disability associated with hip osteoarthritis? A meta-analysis of randomized controlled trials

Objective To determine if clinical guidelines recommending therapeutic exercise for people with hip osteoarthritis (OA) are supported by rigorous scientific evidence. Methods A meta-analysis of randomized controlled trials (RCTs) recruiting people with hip OA and comparing some form of land-based exercise program (as opposed to exercises conducted in the water) with a non-exercise group in terms of hip pain and/or self-reported physical function. Results Thirty-two RCTs were identified, but only five met the inclusion criteria. Only one of the five included RCTs restricted recruitment to people with hip OA, the other four RCTs also recruiting participants with knee OA. The five included studies provided data on 204 and 187 hip OA participants for pain and physical function, respectively. Combining the results of the five included RCTs using a fixed-effects model demonstrated a small treatment effect for pain (standardized mean difference (SMD) −0.38; 95% confidence interval (CI) −0.67 to −0.09). No significant benefit in terms of improved self-reported physical function was detected (SMD −0.02; 95% CI −0.31 to 0.28). Conclusion Currently there is only silver level evidence (one small RCT) supporting the benefit of land-based therapeutic exercise for people with symptomatic hip OA in terms of reduced pain and improved physical function. The limited number and small sample size of the included RCTs restricts the confidence that can be attributed to these results.

Prognostic value of early exercise testing after coronary stent implantation

The clinical value of early exercise stress testing (EST) after coronary stenting to predict long-term clinical outcomes is unknown. Of 1,000 unselected patients who underwent coronary stenting, 446 random patients underwent early EST the day after intervention. Clinical long-term outcomes (41 +/- 20 months) were correlated with normal (n = 314 [70%]) or positive (n = 102 [23%]) EST results. Patients with inconclusive test results (n = 30 [7%]) were excluded from the analysis. Overall mortality was significantly higher in patients with positive EST results (9.3% vs 3.9%, p = 0.04). Major adverse cardiac events and cardiac mortality also tended to be higher in patients with positive stress test results (45.4% vs 35.4%, p = 0.08, and 4.1% vs 1.1%, p = 0.05, respectively). Patients with the combination of positive stress test results and incomplete revascularization appeared to be the group at highest risk for major adverse cardiac events (47.1% vs 33.3% for patients with normal stress test results and complete revascularization, p = NS). Negative stress test results reduced (odds ratio 0.329, 95% confidence interval 0.120 to 0.905, p = 0.031) and a lower ejection fraction increased (odds ratio 0.942, 95% confidence interval 0.897 to 0.989, p = 0.017) the risk for death. In conclusion, an early stress test after coronary stenting provides important prognostic information. Positive stress test results, especially in combination with incomplete revascularization, are associated with higher mortality, a trend toward more repeat revascularization procedures, and higher risk for major adverse cardiac events.

Effect of therapeutic exercise for hip osteoarthritis pain: results of a meta-analysis

OBJECTIVE: Recommendations for lower extremity osteoarthritis (OA) and exercise have been primarily based on knee studies. To provide more targeted recommendations for the hip, we gathered evidence for the efficacy of exercise for hip OA from randomized controlled trials. METHODS: A bibliographic search identified trials that were randomized, controlled, completed by >or=60% of subjects, and involved an exercise group (strengthening and/or aerobic) versus a non exercise control group for pain relief in hip OA. Two reviewers independently performed the data extraction and contacted the authors when necessary. Effect sizes (ES) of treatment versus control and the I(2) statistic to assess heterogeneity across trials were calculated. Trial data were combined using a random-effects meta-analysis. RESULTS: Nine trials met the inclusion criteria (1,234 subjects), 7 of which combined hip and knee OA; therefore, we contacted the authors who provided the data on hip OA patients. In comparing exercise treatment versus control, we found a beneficial effect of exercise with an ES of -0.38 (95% confidence interval [95% CI] -0.68, -0.08; P = 0.01), but with high heterogeneity (I(2) = 75%) among trials. Heterogeneity was caused by 1 trial consisting of an exercise intervention that was not administered in person. Removing this study left 8 trials (n = 493) with similar exercise strategy (specialized hands-on exercise training, all of which included at least some element of muscle strengthening), and demonstrated exercise benefit with an ES of -0.46 (95% CI -0.64, -0.28; P < 0.0001). CONCLUSION: Therapeutic exercise, especially with an element of strengthening, is an efficacious treatment for hip OA.

Heart rate response determines long term exercise capacity after heart transplantation

BACKGROUND: Exercise capacity after heart transplantation (HTx) remains limited despite normal left ventricular systolic function of the allograft. Various clinical and haemodynamic parameters are predictive of exercise capacity following HTx. However, the predictive significance of chronotropic competence has not been demonstrated unequivocally despite its immediate relevance for cardiac output. AIMS: This study assesses the predictive value of various clinical and haemodynamic parameters for exercise capacity in HTx recipients with complete chronotropic competence evolving within the first 6 postoperative months. METHODS: 51 patients were enrolled in this exercise study. Patients were included when at least >6 months after HTx and without negative chronotropic medication or factors limiting exercise capacity such as significant transplant vasculopathy or allograft rejection. Clinical parameters were obtained by chart review, haemodynamic parameters from current cardiac catheterisation, and exercise capacity was assessed by treadmill stress testing. A stepwise multiple regression model analysed the proportion of the variance explained by the predictive parameters. RESULTS: The mean age of these 51 HTx recipients was 55.4 +/- 13.2 yrs on inclusion, 42 pts were male and the mean time interval after cardiac transplantation was 5.1 +/- 2.8 yrs. Five independent predictors explained 47.5% of the variance observed for peak exercise capacity (adjusted R2 = 0.475). In detail, heart rate response explained 31.6%, male gender 5.2%, age 4.1%, pulmonary vascular resistance 3.7%, and body-mass index 2.9%. CONCLUSION: Heart rate response is one of the most important predictors of exercise capacity in HTx recipients with complete chronotropic competence and without relevant transplant vasculopathy or acute allograft rejection.